The development of optical circuitry integrating plasmonic components has prompted a great deal of research work on a worldwide scale during the last decade. In this context and beyond simple passive plasmonic waveguides, integrated plasmonic sources and detectors with integrated plasmons are of genuine practical interest.
Very recently, plasmonic detectors based on the detection of a photocurrent in a semi-conductor have been described in the literature. The plasmonic guide serves as electrode for the measurement of the photocurrent. Such components are dedicated either to studies of phenomena in quantum optics, or to applications of plasmon-assisted integrated optics.
By way of example, it is possible to cite a type of plasmon-based integrated detector using a Schottky barrier but this mode of detection is necessarily limited to very attenuated guided plasmon modes propagating at the interface between a metal and a semi-conductor. An example of such a detector is described by A. Akbari, P. Berini, Appl. Phys. Lett., 95, 021104, (2009).
Moreover, from the point of view of a plasmonic component, the use of semi-conductors imposes draconian fabrication constraints (compatibility with CMOS fabrication processes), high cost and the necessity to work on specific substrates.
Another type of device relying on a thermo-resistive effect makes it possible to detect the power propagating along a plasmonic guide. An example of this type of device is presented by S. Bozhevolnyi, T. Nikolajsen, K. Leosson, in the publication “Integrated Power monitor for long range surface plasmon polaritons”, Optics Communication, 255, 51, (2005). Such a detector requires a waveguide length sufficient to allow the detection of a variation in resistivity, thus rendering the miniaturization of the device difficult; moreover these detectors exhibit high response times of the order of a millisecond.
The measurement of the power conveyed by non-guided plasmon modes can, however, be carried out in a simple and effective manner by virtue of a thermoelectric scheme. The detection of the simple excitation of a plasmon mode by a thermoelectric system is for example described in U.S. Pat. No. 5,792,667: in this instance this entails detecting the excitation of a plasmon mode on an extended thin film for which no notion of guidance of the plasmon mode intervenes. It does not therefore entail detecting the power propagating along a plasmonic guide, the notion of guidance comprising the notion of lateral confinement of the plasmon mode. The same holds as regards the publication by R. A. Innes and J. R. Sambles, “Simple detection of surface plasmon-polaritons”, Solid State Communications, 56, 493, (1985). In these two examples, the thermoelectric scheme is implemented to measure the optical reflectivity of the system integrating an extended thin metallic layer on which a surface plasmon is excited and not to obtain information on an arbitrary power associated with an optical or plasmonic guided mode.